Explosion and fire release ventilator



June 6, 1967 w. a. KORFF 3,323,438

EXPLOSIONVAND FIRE RELEASE VENTILATOR Filed Aug. 23, 1965 2 Sheets-Sheet 1 INVENT WOLFEHM G- KOE9% W,m,m,

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ATTOE NEY5 United States Patent 3,323,438 EXPLOSION AND'FIRE RELEASE VENTILATOR Wolfram G. Korif, Granada Hills, Calif., assignor to Western Engineering ,& Mfg. Co-., Los Angeles, Calif., a corporation of California 7 v Filed Aug. 23, 1965, SenNo. 481,746

- 9 Claims. (Cl. 98'42) The present invention relates to aventilat or and, more particularly, to a ventilator which is adapted for both maual and automatic actuation to open and vent the interior of a building particularly in'the event of a fire or explosion.

It is extremely important to vent the noxious gases and accumulations of pressure which occur during a building fire. Concentrations of smoke and fumes complicate the firefighters task' and frequently contribute to the intensity of the fire. Moreover, failure to immediately vent the destructive force of an explosion can and often does structurally damage'the building because of the inability of the building walls and the roof to withstand the tre mendous forces exerted against them from the sudden build-up of internal buildingpressures during an explo- To protect against the build-up of noxious gases and pressure which usually accompanies a'fire, many buildings include ventilators in their roofs. Generally, such ventilators include doors hinged to the roof of'the build ing for closing a part in the roof. An actuating mechanism is connected to the doors to rapidly and automatically open'the doorswhen the pressure or' temperature within the building reaches a predetermined value. The actuating mechanism also'may be manually operated from Within the building and the doors may be manually opened from without the building.

Although-most present-day building ventilators theoretically provide sufficient protection for a building in case offire or pressure build-up, they suffer unfortunately from many practical problems andlimitations. First of all, commercially available building ventilators are designed to operate only at a fixed value of internal pressure, in most cases 10 lbs/sq. ft. Although this may be satisfactory for certain types of unpr'essuriz'ed buildings, for other types it is not.- Also, many buildings are maintained at a positive pressure to prevent dust and otherforeign In addition, the actuating mechanism of most building ventilators are heavily spring biased to rapidly open the ventilators doors upon operation thereof. Als'o, chains, cables, and/or rods are usually connected tothe ends of the doors to limit the travel of the doors in opening. Such combinations a'r'e capable of, and in practice frequently cause, the doors of the ventilators to rebound and rapidly reclose after the automatic opening thereof by thebuildup of pressures or temperatures within the associated buildings. The chains, cables, and spring-biased actuating mechanisms also interfere with the safe access of firefighters to' the building throu'gh the ventilators.

Commercially available building ventilators are also relatively expensive and the actuating mechanisms thereof are complex and difiicult tomount.

Inview of the foregoing, it is an'object of the present vention to provide an improved building ventilator 3,323,438 Patented June 6, 1967 which is adapted to be actuated either manually or auto matically to vent through an associated opening, the products of a fire or an explosion within a building.

Another object of the present invention is to provide a building ventilator of the aforementioned character which includes means for holding the doors of the ventilator open after the initial shock wave of an explosion has subsided. This pre'ventsthe development in the building of highly-dangerous negative pressures immediately subsequent to the explosion, and also precludes subsequent successive accumulations of explosive gases or vapors. I 1

A further object of the present inventionist'o' provide a ventilator of the'aforementioned character in which the actuating mechanism therefor occupies a minimum of space to permit firefighters to have access to the building through the opening which is beingvented.

Still another object of the present invention is to provide a ventilator of the aforementioned character in which the actuating mechanism is automatically operable through release of a fusible link when the building tern: peratures reach a predetermined level; In this regard,--it is a feature of the present invention that the ventilator may bereset for subsequent operation by merely replacing the fusible link and closing the ventilator doors. I

A still further object of the present invention is to'provide an improved ventilator of the aforementioned character in which the ventilator may be manually opened from outside the building or from inside the building by pulling on a chain or the like attached tothe actuating mechanism.

Another object of the present invention is to provide a ventilator of the aforementioned character including releaseable means for locking the ventilator when it is desired to prevent opening thereof from outside the building.

A further object of the present invention is to provide a ventilator of the aforementioned character which is simple to operate, easy to maintain, and relatively inexpensive to manufacture and install.

Still another object of the present invention is to provide a ventilator of the aforementioned character wherein the actuating mechanism thereof is adjustable to'control the internal building pressure and force requiredto operate the ventilator within a relatively wide range of values.

A stillfurther object of the present invention is to pro vide a ventilator of the aforementioned character wherein the actuating mechanism is a self-contained and complete subas'sembly which may be easily and rapidly mounted in the ventilator.

Another object of the present invention is to provide a ventilator of the aforementioned character which after operation provides an unobstructed and safe access to the building through the roof thereof. 1

The foregoingas well as other objectsand advantages of the present invention will become apparent from the following detailed description when taken with-the drawings which, by way of example only, illustrate one form of building ventilator embodying the features of the present invention.

In the drawings:

FIGURE 1 is a persepctive view of the ventilator of the present invention with an outer portion broken way to expose the actuating mechanisms for the ventilator;

FIGURE 2 is a fragmentary sectional view ofthe ventilator taken along the line 2-2 of FIGURE 1; 7

FIGURE 3 is a sectional view similar to FIGURE 2 showing the actuating mechanism and ventilator in an operated condition and in phantom outline illustrating the ventilator in its closed position similar to FIGURE 2; and

FIGURE 4" is a fragmentary sectional side view of a -portionof the act-uatingmechanism for theve'ntilator illustrating the operation of the actuating mechanism after breakage of a fusible link due to the build-up of high temperatures within the building associated with the ventilator.

Referring to the drawings and particularly to FIGURE 1 thereof, there is illustrated one form of building ventilator of the present invention. The ventilator is represented generally by the numeral and includes a supporting structure or base 12 adapted to be positioned or mounted adjacent a rectangular curb 14 defining a roof opening 16 of the building from which gases are to be vented. The base 12 pivotally mounts a pair of doors 18 so that the doors may be actuated to open positions by a pair of actuating mechanisms 20 connected between the door 18 and the base 12.

The base .12 is preferably made of corrosion-resistant sheet metal and includes parallel, elongated sides 22 rigidly secured or welded at their extremities to a pair of ends 24 whose upper margins converge inwardly from the sides 22 to form a generally triangular transverse section having a generally V-notched apex 26 for supporting the doors 18 in their closed positions.

The sides 22 and ends 24 of the base 12 preferably are fitted upon the curb 14 in a weatherproof fashion and for this purpose include flashing consisting of a horizontally-oriented shelf portion 28 which rests on top of the curb 14 and a skirt section 30 which depends from the shelf adjacent the outer side of the curb 14. The portion 28 and section 30 extend about the complete periphery of the ventilator 10 and any suitable fasteners (not shown) are used for securernent thereof to the curb 14 to hold the ventilator 10 in position adjacent the roof opening 16.

The base 12 also includes an elongated, generally V- shaped gutter 32 extending between and connected to the V-notched apices of the triangularly-shaped ends 24 to rigidify the ends 24 for the support of the doors 18 and to provide a path for the flow of water off the top of the ventilator 10.

The pivotal mounting for the rectangular doors 18 to the base 12 may be provided by any suitable hinge means effective to firmly and pivotally hold the doors in position for actuation by the actuating mechanism 20. In this regard, it will be apparent that only one hinged door may be utilized, if desired, the present description of the ventilator 10 employing two doors 18 merely being exemplary. Also, the door opening and closing apparatus operates equally well upon either a single door or a pair of doors 18.

Here, each door 18 is hinged at its ends to rotate or swing about a horizontal axis. To this end, a pair of flanges 34 depend from the inner margins of each door 18 adjacent the base 12. A pair of similar flanges 36 extend horizontally from the edge of each end 24 immediately above the horizontal shelf 28. Horizontal pins 38 extend through openings in the flanges 3.4 and 36 to pivotallyconnect the doors 18 to the base 12 for swinging movement about horizontal and parallel axes.

Each door 18 is extendable to an open position, as shown in FIGURE 3, and retractable to a closed position, as illustrated in FIGURE 2, by one of the actuating mechanisms 20. The actuating mechanisms 20 are the same and will be described with particular reference to FIGURES 2, 3 and 4.

As illustrated, the actuating mechanism 20 includes a channel-shaped support member 40 having outwardlyextending flanges 42 at both ends for connection to the sides 22 of the base 12 by bolts 44. Thus connected, the support member 40 extends across the open-ing 16 normal to' the'horizontal door hinge axis defined by the pins 38.

A forked arm 46 is pivotally connected at one end to the support member 40 to swing about a horizontal axis generally parallel to and adjacent the door hinge axis. To this end, a torsion spring arbor 48 extends between the sides of the forked arm 46 with pins 50 extending through aligned holes in the forked arm and inthe sides of the channel-shaped support member 40. A torsion spring 52 is coiled around the arbor 48 with one end extending through a bottom hole 54 in the base of the support member 40, and an opposite end extending from the arbor and through an opening 56 in a crosspiece 58 between the sides of the forked arm 46. The torsion spring 52 continuously urges the forked arm 46 to swing about the arbor 48 away from the opening 16 in the roof of the building and toward the door 18.

Movement of the forked arm 46 toward the door 18, however, is resisted by a combination of a connector bar 60, an inverted Z shaped trigger 70, and the door. The connector bar 60 is hinged at one end to the inside of the door 18 by a hinge 62 comprising a bifurcated hinge plate 64 having a pair of spaced arms 67. The hinge plate 64 is connected to the inside of the door by a pair of bolts 66 and a pin 68 extends horizontally through the arms 67 and an aligned opening in the end of the connector bar 60 to support the bar 60 for swinging movement about an axis generally parallel to the door hinge ax1s.

The opposite end of the connector bar 60 passes through the forked arm 46 just forward of the cross-piece 58 and is there pivotally connected by a pin 76 to the end of a lower arm 71 of the trigger 70. In addition to the lower arm 71, the trigger 70 includes an upper arm 72 and a middle arm 73 between the-upper and lower arms. A horizontal pivot pin 74 passes through the forked arm 46 and through an opening in the trigger 70 at a junction of the lower and middle arm to pivotally connect the trigger for swinging movement about a horizontal axis generally parallel to the door hinge axis.

The upper arm 72 of the trigger 70 is continuously urged toward the hinge 62 and the connector bar 60. To this end, an elongated coil spring 78 is connected at one end to the connector barnear the hinge 62 with an opposite end extending around and connected to the hooked end 80 of a bolt 79. The bolt 79 passes through a hole in the upper arm 72 of the trigger 70 and there threadedly receives a nut 81 to tightly secure the bolt to the trigger. By tightening or loosening the nut 81, the tension in the coil spring 78 may be adjusted to control the value of the force continuously urging the upper end of the trigger 70 toward the connector bar 60 and, by the same token, the force necessary to swing the trigger away from the connector bar to engage a latch 82 and operate the actuating mechanism 20.

More particularly, when the door 18 is closed against the gutter 32, the forked arm 46 is prevented from turning about the arbor 48 to open the door, by a generally L-shaped latch 82. The latch 82 is pivotally connected at the junction of its vertical leg and horizontal foot to the support member 40 for swinging movement about an axis generally parallel to the door hinge axis. To this end, a pair of pins 83 extend from opposite sides of the latch and through aligned holes in the opposing sides of the channel shaped support member 40 adjacent and just forward of the end of the forked arm 46. The latch 82 is continuously urged toward the end of the forked arm 46 :by a spring 85 stationed around a bolt 86 extending upward from the base of the support member. The upper end of the spring 85 is seated within a socket 87 in the foot 88 of the latch and urges a hook portion 84 of the latch toward and over the top of the forward end of the forked arm 46 as illustrated in FIGURE 2.

The portion 89 of the leg of the latch 82 above the hook 84 is curved and faces the trigger 70 to define a trigger contact surface for the latch. In this regard, a latch release means 90 extends from the middle arm 73 of the trigger toward the trigger contact portion 89 of the latch. Here the latch release means comprises a threaded bolt extending through a threaded hole in the trigger and to receive a nut 91 for securing a bolt to the trigger. By turning the bolt 90, the bolt may be extended or retracted from the trigger 70 toward and away from the latch 82. In this manner, the travel of the trigger 70 toward the latch 82 necessary to engage and release the latch from the forked arm 46 and operate the actuating mechanism 20 is selectively controllable. Accordingly, the bolt 90 may be adjusted such that there is relatively'large space between the head of the bolt and the latch 82 requiring the trigger to travel a relatively long distance to engage and release the latch. Alternatively, and at an opposite extreme of adjustment, the bolt may be moved to contact and even slightly pivot the latch 82 away from the end of the forked arm 46 with the hook 84 just engaging the arm to define a hair-trigger operating conditionfor the actuating mechanism 20.

The movement of the trigger 70 to engage and release the latch 82 from the forked arm 46 may be caused by an increase of pressure within the building. In particular, as the pressure within the building increases, the force acting outwardly on the inside of the door 18v increases and is transmitted through the connector bar 60' to the lower end of the trigger 70. When the torque caused by the upward force acting on the lower end of the trigger 7'0 slightly exceeds the torque caused by the spring force acting on the upper arm 72 of the trigger, the trigger rotates about the pivot pins 74 and the door 18 opens slightly. As the trigger 70 pivots, the head of the bolt 90 moves against the trigger contact portion 89 of the' latch 82' causing the latch to swing away from the end of the forked arm 46. When the hook 84 of thelat'ch' separates from the forked arm, the torsion spring 52 causes the forked arm to swing rapidly about the arbor 48 to carry the actuating mechanism 20 and the door 18 from it's closed position in FIG- URE 2 to its open position illustrated in FIGURE 3.

In the open position, the torsionspr'ing 52 engages an adjustable stop member 92 connectedto the support member 40 between the arbor 48 and the side 22 of the base 12. The stop member 92 haults the outward swinging movement of the forked" arm 46 and hence defines the open position for the door 18. Inthis respect, it isof course appreciated that the torsion spring continuously urges the forked arm46 and door 1'8 outwardly to the open position defined-by the stop 92 to insure against a possible closure of the door after the torsion spring initially bounces against the stop member and after the initial shock Wave of an explosion within the building has subsided.

As indicated, the stop member 92 is adjustable along the support 40. This is accomplished by first loosening a nut 94' Which secures the stop member to a bolt 93 extendingv from the support member 40 through an elongated slot 95 in the stop member, thereby sliding the stop member along the support member 40, and againtightening the nut 94'. In this manner, the open position may be adjusted with. the door 18 held eitherin avertical or leaning in or out direction, as desired.

As previously described, the space between the end of the nut 90 and the trigger70 may be controlled to regulate the travel of the trigger 70 required to operate the latch 82; and the trigger maybe preset for hair-trigger operation with the head of the bolt in contact with the latch with the door closed. This feature of adjustability is beneficial in shortening the elapsed time between the start of door travel and the release of the latch. Although the reduction in time may be only in the order of a few milliseconds, the damagefromexplosions to abuilding is generally done in'a matter of milliseconds.-

As also previously described, the tension in the coil spring 78 between the trigger 70 and the connector bar 60 may be controlled. Alternatively, the co'ilsprin'g 78 may be replacedby heavier or lightersprings, as-desired, to control the spring force acting onthetrigger70 toward the connector bar 60and hence the force required to swing the trigger to'disengage" the latch 82. Since the lever arm between the pivot p'in' 7 4" andthe' connection for the spring78 tothe trigger 70'is m'uchgre'ater than the lever arm betweenthe pins 74 and 76, the door opening force produced by an increase in the internal pressure within the building must be substantially greater than the force of the spring 78. This allows the use of relatively light springs to control the internal building pressure necessary to operate the actuating mechanism 20 and open the door 18. Inthis regard, by adjusting the tension in the spring 78, itis possible to vary the internal building pressure required to pen the door from between about 5 to about 4'0 lbs/sq. ft. This feature makes the ventilator 10 of the present invention ideally suited to use in both pressurized and non-pressurized buildings of all types.

The same general operation of the actuating mechanism 20- to open the door 18 occurs when an inspector, fireman, or workman pulls onthe upper end of the door from outside the building. In such a case, the workman lifts upwardly on the end of the door adjacent the gutter 32 to cause the connector bar 60 to rotate the trigger 70 into contact with the latch 82. The trigger 70 disengages the latch 82 from the forked arm 46 to release the actuating mechanism 20 and rapidly open the door 18 under the influence of the torsion spring 52.

In order to prevent unauthorized entrance to the building through the ventilator 10 during certain hours, such as at nighttime after operations in the building haveceased, the actuating mechanism 20 may be furnishedwith a locking rod 96 between the connecting bar 60 and the upper end of the trigger 70. As illustrated in FIGURES 1,-

and in phantom outline in FIGURES 2 and 3, the locking rod 96 is-releasa'bly connected at one end within a hole in the connecting bar 60 and is threaded at its opposite end and passes through a hole in the upper endof the trigger 70 to receive nuts 97 on either side of the trigger which releasably secure the rod in place. Thelocking rod- 96 makes the connector bar 60'and trigger 70 a rigidunit and prevents an intruder from opening the door 18 by pulling upward on the end adjacent the gutter 32.

In this manner, the rods'make the ventilator burglar proof,

but do so without effecting the fire release or manual pull chain mechanism to be described hereinaften Ihus, even though the ventilator 10- may be locked against outside influence, the doors 18 will still openautomatically in case of accidental fire.

In addition to the bolt 90, the middle arm 73 of the trigger 70 also carries a threaded bolt 98. The bolt 98 passes through a threaded hole in the middle arm to receive a nut 99 for securing the bolt in place. By turning the bolt 98, the bolt is extendable and retractable from the trigger 70'towardthe connector bar 60 to engage the edge thereof. In this respect, the bolt 98 acts as an adjustable stop for limiting the turning of the connector bar 60 about the hinge 62 and is of particular value in the initial set-up of the ventilator to insure that the door 18 fully closes just as the latch 82 locks the forked arm 46 in place. In particular, after the base 12, doors 18 and actuating mechanisms 20 have been connected in place, each door 18 is closed until its associatedlatch' 82 engages and locks against theend of the forked arm 46. The bolt 98 is then turnedto engage the connector bar 60 and to rotate the' connector bar about the hinge 62. Since the connector bar 60 is pivotally connected to the trigger 70' and'therethrough to theforked arm 46, this movement of the connector ba'rlcauses the door 18 to swing'toward and close tightly against the marginal edge of the gutter 32. This insures that the door 18 is completely closed and sealed when the'a'ctuating mechanism 20 is in its locked condition withthe latch 82 engaging the forkedarm 46. Accordingly, the'bolt 98 providesa manual adjustment for compensating forminor inaccuracies in thema'nufacture of the ventilator 10 or the mounting thereof on the curb 14.

As previouslyindicated, the" ventilator 10 includes a channel-shaped support member 40 along a vertical center line of the ventilator 10.

The actuating assembly 100 also includes a fusible link 102 adapted to fuse or melt and break at a predetermined building temperature, such as 212 F. One end of the link 102 is connected to the hooked end 103 of a bolt 104 which extends vertically through a hole 105 in the top 106 of a bridge 101. A coil spring 107 extends around the bolt 104 above the top of the bridge 101 and is secured in place by a nut 108 threadedly received by the end of the bolt. The nut 108 presses tightly on the upper end of the coil spring 107 to compress the coil spring between the nut and the top of the bridge. By turning the nut 108, the compression of the coil spring 107 can be adjusted.

The opposite end of the link 102 receives a hooked end 109 of a bolt 110. The bolt 110 extends vertically through a hole 111 in the bottom of a support member 40 and there receives a coil spring 112. The coil spring 112 is secured in place by a cap nut 113 threadedly received by the bottom end of the bolt 110. A chain 114 is connected to the cap nut 113, which presses tightly against the bottom of the coil spring 112 to compress the coil spring against the bottom of the support member 40.

To complete the assembly 100, a hammer plate 115 is Welded to the bolt 110 and extends within the bridge 101 directly over the foot of the latch 82.

The actuating mechanism 100 may be operated to release the latch 82 from the forked arm 46 and operate the mechanism 20, either by pulling down on the chain 114 or by breakage of the fusible link 101. The operation of the assembly 100 in response to a pulling on the chain 114 is diagrammatically illustrated in FIGURE 3 while actuating by breakage of the fusible link 101 is represented in FIGURE 4.

When the chain 114 is pulled, a downward force is exerted on the hammer plate 115. The downward force compresses the coil spring 107 as the hammer plate is moved with the link 101 and bolts 104 and 110 downwardly to engage the foot of the latch 82. Upon engaging the latch '82, the hammer plate 115 causes the latch to rotate about the pins 83 and release the forked arm 46, thereby operating the actuating mechanism to open the door .18. As illustrated, the hammer plate 115 is located over the foot of the latch for each actuating mechanism 20. Therefore, the pulling of the chain simultaneously operates both actuating mechanisms 20 to open both of the doors 18 for the ventilator 10. Also, by turning the nut 108 the force necessary to operate the assembly 100 by pulling on the chain 114 may be selectively controlled.

The same movement of the hammer plate 115 occurs upon a breakage of the fusible link 101, only much faster. In particular, when the temperature within the building reaches and exceeds the predetermined breakage temperature for the fusible link 101, the fusible link parts allowing the coil spring 112 to rapidly drive the hammer plate 115 downward against the food of the latch 82. This produces a rapid turning of the latch and release of the forked arm 46 to operate the actuating mechanism 20 and open the doors 18.

From the foregoing description, it is appreciated that the present invention provides an improved building ventilator which is adapted to be actuated either manually or automatically from within or without the building to vent through an associated opening, the products of a fire or an explosion within a building. Once the ventilator is operated, the doors thereof are held open after the initial shock wave of an explosion has subsided thereby preventing the development in the building of highlydangerous negative pressures immediately subsequent to the explosion and also precluding the accumulation of explosive gases or vapors within the building.

The actuating mechanism 20 for the ventilator is extremely compact and occupies a minimum of space to permit firefighters to have access to the building associated therewith through the opening which is being vented. Also, when the doors are opened, the main spring 52 of the actuating mechanism is automatically released and there is no dangerously spring-loaded arms which may be accidentally triggered by workmen or firemen climbing through the opening being vented. Further, the actuating mechanism 20 is a self-contained and complete subassembly which may be easily and rapidly mounted in the yentilator simply by attaching four bolts to each side 22 and each door 18 in the ventilator.

In addition, the ventilator may be locked to prevent unauthorized access to the building through th eventilator from outside the building, while maintaining intact the fire release and manual pull release of the actuating mechanism 20 to open the doors from within the building.

Also, the actuating mechanism 20 is adjustable to control the internal building pressure as well as the outside manual force necessary to operate the actuating mechanism and open the doors.

Furthermore, by changing the length of the connector bar 60 and the support member 40, the actuating mechanism 20 can be adapted to suit a multitude of door sizes and unit configurations.

While a particular form of building ventilator has been described in some detail, changes and modifications may occur to those skilled in the art without departing from the spirit of the present invention. It is, therefore, intended that the presentinvention be limited in scope only in terms of the following claims.

I claim:

1. A building ventilator comprising:

a door supported for swinging movement about a predetermined axis between open and closed positions over an opening in a building;

a first arm pivotally mounted at a first end portion for swinging movement within said opening about an axis adjacent and generally parallel to said predetermined axis;

means urging a second end portion of said first arm to swing toward said door;

a second arm pivotally connected at a first end portion to said door for swinging movement about an axis generally parallel to said predetermined axis;

a third arm pivotally connected at a first end portion to a second end portion of said second arm and at a point spaced from said first end portion to said first arm for turning about axes generally parallel to said predetermined axis;

spring means between a second end portion of said third arm and said second arm for continuously urging said second end to swing toward said second arm about said point;

a latch pivotally mounted for turning about an axis generally parallel to said predetermined axis to engage said first arm when said door is in said closed position to prevent turning of said first arm toward said door thereby locking said door in said closed position;

means continuously urging said latch to engage said first arm;

latch release means carried by said third arm for engaging said latch to disengage saidlatch from said first arm upon a swinging of said second end portion of said third arm away from said second arm;

a fusible link; means supporting one end of said link; a hammer member connected to an opposite end of said link; and means continuously uring said hammer member away from said ling and towards said latch to strike and release said latch from said arm upon a breakage of said link.

2. A building ventilator according to claim 1 and including hand-gra'spable means extending from said hammer member for pulling said hammer member into engagement with said latch to release said latch from said first arm.

3. An actuatmg mechanism for a building ventilator including a door mounted for swinging movement about a predetermined door axis between open and closed positions over an opening in a building; said mechanism comprising;

support means adapted to extend across said opening:

a first arm pivotally connected at its inner extremity to said support means for swinging movement within said opening about an axis adjacent and generally parallel to said door axis;

first bias means connected to said first arm and said support means and urging the outer extremity of said first arm away from said support means and toward said door;

a second arm extending generally upwardly of said opening for pivotal connection at its upper extremity to said door;

a third arm extending generally upwardly of said opening, pivotally connected at its lower extremity to the lower extremity of said second arm, and pivotally connected upwardly of its lower extremity to the inner extremity of said first arm;

second bias means connected to the upper extremity of said third arm and to said second arm and urging said second arm to swing toward said third arm and about its pivotal connection to said third arm;

a latch pivotally connected to said support means for movement into and out of latching engagement with the inner extremity of said first arm;

third bias means connected between said support means and said latch and urging said latch into said latching engagement with said first arm;

first latch release means carried by said third arm and adjustable thereon to project an adjustable distance from said latch whereby an upward force on said door tending to pull on said second arm and pivot said third arm upon said first arm effects engagement of said first latch release means against said latch to pivot said latch out of said latching engagement against the bias of said third bias means; and a second latch release means operable to pivot said latch against the bias of said third bias means and out of said latching engagement independently of engagement between said first latch release means and said latch.

4. An actuating mechanism according to claim 3 and including door adjustment means carried by said third arm and adjustable thereon to project into engagement with said second arm when said door is seated shut and said latch is in said latching engagement to thereby adjust the seated position of said door.

5. An actuating mechanism for a building ventilator including a door mounted for swinging movement about a predetermined axis between open and closed positions over an opening in a building, comprising:

a support member extending across said opening;

a first arm pivotally connected at a first end portion to said support member for swinging movement within said opening about an axis adjacent and generally parallel to said predetermined axis;

first spring means connected to said support member and said first arm for continuously urging a second end portion of said first arm to swing away from said support member and toward said door;

a second arm pivotally connected at a first end portion to said door for swinging movement about an axis generally parallel to said predetermined axis;

a third arm pivotally connected at a first end portion to a second end portion of said second arm and at a point spaced from said first end portion of said third arm to said first arm for turning about axes generally parallel to said predetermined axis;

second spring means between a second end portion of said third arm and said second arm for continuously urging said second end to swing toward said second arm about said point;

a latch pivotally connected to said support member for turning about an axis generally parallel to said predetermined axis to engage a second end portion of said first arm when said door is in said closed position to prevent turning of said first arm toward said door thereby locking said door in said closed position;

means continuously urging said latch to engage said first arm;

latch release means carried by said third arm for engaging said latch to disengage said latch from said first arm upon swinging of said second end portion of said third arm away from said second arm;

a fusible link;

a hammer member connected to one end of said link;

and a normally balanced spring assembly carried by said support member and connected to said link including a third adjustable spring means extending from said support member for urging an opposite end of said link away from said latch and a fourth spring means extending from said support member for urging said one end of said link toward said latch such that said hammer strikes and releases said latch from said first arm upon a breakage of said link.

6. The actuating mechanism of claim 5 including a hand-graspable means extending from said hammer for manually pulling said hammer into engagement with said latch to release said latch from said first arm.

7. The actuating mechanism of claim 5 including stop means for halting movement of said door after release of said latch and after a predetermined travel of said door to define said open position of said door.

8. The actuating mechanism of claim 5 including means for adjusting said second spring means to control the force required to swing said second end portion of said third arm away from said second arm.

9. The actuating mechanism of claim 5 wherein said latch release means is extendable and retractable toward and away from said latch to control the length of travel of said third arm away from said second arm required to release said latch.

References Cited UNITED STATES PATENTS 1,787,623 1/1931 Harriett 9886 2,329,476 9/1943 Livingston.

2,923,226 2/1960 Wasserman et al. 9842 X 2,940,377 6/ 1960 Darnell et al. 9886 3,182,581 5/ 1965 Von Poederoyen et a1. 98-8 6 X 3,251,158 5/1966 Shapiro 49--7 X ROBERT A. OLEARY, Primary Examiner.

5 MEYER PERLIN, Examiner.

W. E. WAYNER, Assistant Examiner, 

1. A BUILDING VENTILATOR COMPRISING: A DOOR SUPPORTED FOR SWINING MOVEMENT ABOUT A PREDETERMINED AXIS BETWEEN OPEN AND CLOSED POSITIONS OVER AN OPENING IN A BUILDING; A FIRST ARM PIVOTALLY MOUNTED AT A FIRST END PORTION FOR SWINGING MOVEMENT WITHIN SAID OPENING ABOUT AN AXIS ADJACENT AND GENERALLY PARALLEL TO SAID PREDETERMINED AXIS; MEANS URGING A SECOND END PORTION OF SAID FIRST ARM TO SWING TOWARD SAID DOOR; A SECOND ARM PIVOTALLY CONNECTED AT A FIRST END PORTION TO SAID DOOR FOR SWINGING MOVEMENT ABOUT AN AXIS GENERALLY PARALLEL TO SAID PREDETERMINED AXIS; A THIRD ARM PIVOTALLY CONNECTED AT A FIRST END PORTION TO A SECOND END PORTION OF SAID SECOND ARM AND AT A POINT SPACED FROM SAID FIRST END PORTION TO SAID FIRST ARM FOR TURNING ABOUT AXES GENERALLY PARALLEL TO SAID PREDETERMINED AXIS; SPRING MEANS BETWEEN A SECOND END PORTION OF SAID THIRD ARM AND SAID SECOND ARM FOR CONTINUOUSLY URGING SAID SECOND END TO SWING TOWARD SAID SECOND ARM ABOUT SAID POINT; A LATCH PIVOTALLY MOUNTED FOR TURNING ABOUT AN AXIS GENERALLY PARALLEL TO SAID PREDETERMINED AXIS TO ENGAGE SAID FIRST ARM WHEN SAID DOOR IS IN SAID CLOSED POSITION TO PREVENT TURNING OF SAID FIRST ARM TOWARD SAID DOOR THEREBY LOCKING SAID DOOR IN SAID CLOSED POSITION; MEANS CONTINUOUSLY URGING SAID LATCH TO ENGAGE SAID FIRST ARM; LATCH RELEASE MEANS CARRIED BY SAID THIRD ARM FOR ENGAGING SAID LATCH TO DISENGAGE SAID LATCH FROM SAID FIRST ARM UPON A SWINGING OF SAID SECOND END PORTION OF SAID THIRD ARM AWAY FROM SAID SECOND ARM; A FUSIBLE LINK; MEANS SUPPORTING ONE END OF SAID LINK; A HAMMER MEMBER CONNECTED TO AN OPPOSITE END OF SAID LINK; AND MEANS CONTINUOUSLY URGING SAID HAMMER MEMBER AWAY FROM SAID LING AND TOWARDS SAID LATCH TO STRIKE AND RELEASE SAID LATCH FROM SAID ARM UPON A BREAKAGE OF SAID LINK. 